Cages and bed linens tested negligible for estrogenicity by the E-SCREEN assay; water was supplied from glass bottles only

Cages and bed linens tested negligible for estrogenicity by the E-SCREEN assay; water was supplied from glass bottles only. BPA- and vehicle-treated groups throughout the examined time-points. Red indicates change in methylation status.(TIF) pone.0099800.s003.tif (4.0M) GUID:?CB26D1CF-D0C6-40D7-A34E-4E2BEB13B3ED Table S1: Genes with significant gene expression changes.(DOC) pone.0099800.s004.doc (57K) GUID:?43CECA8D-C853-4DA5-B88A-B7E6088667F5 Abstract Exposure to environmental estrogens (xenoestrogens) may play a causal role in the increased breast cancer incidence which has been observed in Europe and the US over the last 50 years. The xenoestrogen bisphenol A (BPA) leaches from plastic food/beverage containers and dental materials. Fetal exposure to BPA induces preneoplastic and neoplastic lesions in the adult MM-589 TFA rat mammary gland. Previous results suggest that BPA acts through the estrogen receptors which are detected exclusively in the mesenchyme during the exposure period by directly altering gene expression, leading to alterations of the reciprocal interactions between mesenchyme and epithelium. This initiates a long sequence of altered morphogenetic events leading to neoplastic transformation. Additionally, BPA induces epigenetic changes in some tissues. To explore this mechanism in the mammary gland, Wistar-Furth rats were exposed subcutaneously via osmotic pumps to vehicle or 250 g BPA/kg BW/day, a dose that induced MM-589 TFA ductal carcinomas to 2.5, 25, 250 and 1000 g BPA/kg body weight/day had significantly increased rates of ductal hyperplasia; additionally, those exposed to the two highest doses developed ductal carcinoma at postnatal days (PND) 50 and 95 [28]. These highly proliferative lesions contained an increased number of cells expressing estrogen receptor alpha [28]. BPA binds and activates estrogen receptors alpha and beta [29]. During the period of exposure, i.e. prenatally, these estrogen receptors are detectable only in the primary mesenchyme. Because the propensity to develop mammary cancer manifests long after cessation of exposure, the plausible events following BPA exposure may include extemporaneous gene expression that underlies the altered stroma-epithelium interaction observed in the MM-589 TFA fetal mammary gland, as well as long-lasting changes in the epigenome. Epigenetic changes are known to regulate gene expression and are thought to be involved in normal development and cancer [30], [31]. Maternal exposure to 20 g BPA/kg/day induces genome-wide epigenetic alterations in the forebrains of mice at embryonic day (E) 12.5 and E14.5 [32]. Neonatal exposure of rats to 10 g BPA/kg or to 0.1 g estradiol/kg induced alterations in DNA methylation patterns of multiple genes in the prostate. BPA also increased MM-589 TFA the susceptibility of the prostate of these animals to adult-onset precancerous lesions following exposure to an additional carcinogenic stimulus (i.e., treatment with androgen and estrogen) [33]. Prenatal BPA exposure also leads to hypomethylation of the estrogen-responsive gene Hoxa10 in the uterus and concomitant perturbation of the developmental regulation of uterine estrogen response in mice [34]. Despite accumulated evidence linking BPA exposure to mammary carcinogenesis, the effect of fetal exposure to BPA on the mammary gland epigenome remains unexplored. In the present study, we have monitored BPA serum concentrations in dams in order to relate internal dose to the effects of BPA in the mammary gland. We also examined the effect of such prenatal exposure to BPA on the genome-wide DNA methylation status of the mammary gland during postnatal development and explored potential cues linking epigenetic alterations to breast carcinogenesis during adulthood. We conclude that BPA exposure, at doses within the range of concentrations reported in bio-monitoring studies, is associated with genome-wide epigenetic changes and relevant transcriptional changes at all the time points studied, from the end MM-589 TFA of exposure (PND4) to adulthood, when intraductal hyperplasias and ductal carcinomas (DCIS) are observed. Methods Animals Sexually mature female Wistar-Furth rats (8-week-old; Harlan, Indianapolis, IN) were maintained in temperature- and light-controlled (14-h light, 10-h dark cycle) conditions at the Tufts University School of Medicine animal facility. All p38gamma experimental procedures were approved by.